Distribute new exodusII.h dependency

It's basically a no-op, but it's necessary to allow user codes to
include exodusII.h, which utilities like exodiff in Moose may expect
from us.

contrib/exodusii/v8.11/exodus/Makefile.am

@@ -3,7 +3,8 @@
 # is present. since we've implicitly guaranteed this for ~10 years
 # no need to break that trust now.
 includedir      = $(prefix)/include/libmesh
-include_HEADERS = include/exodusII.h
+include_HEADERS = include/exodusII.h \
+                  sierra/exodus_config.h
 
 pkg_cppflags = -I$(srcdir)/include -I$(srcdir)/sierra $(NETCDF_INCLUDE) $(EXODUS_NOT_NETCDF4_FLAG)
 pkg_sources  = \